The light sources used in lighting systems, for example gas discharge lamps or LEDs, are supplied the appropriate operating voltage or appropriate operating current via operating devices. The operating devices generate the operating voltage or the current from the AC grid or from a DC voltage source. In order to be able to switch on or switch off and dim the light sources separately, the individual operating devices are controllable from a control center via a bus. Each operating device often contains at least one control IC, which, in addition to the control, is also responsible for the communication with the control center and with external sensors etc. Active semiconductor ICs operate on a low voltage of a few volts. This low voltage is often drawn from clocked units during steady-state operation. Before these clocked units can operate properly, a so-called “runup voltage” needs to be present which enables, for example, the startup of the control IC in the operating device, which the result that said control IC can then actuate the clocked units, for example. In order to always provide a runup voltage for the control ICs, the operating devices in bus-controlled lighting systems have until now also been connected to the AC grid in the inactive state, i.e. when the light sources to be supplied by said operating devices are switched off (when the runup energy is recovered by a so-called runup resistor, for example, with the result that corresponding standby losses arise.